1. Patients that meet the American-European Consensus Conference criteria for ARDS [(1) Widespread pulmonary infiltrates; (2) Pulmonary capillary wedge pressure 18 mmHg; (3) PaOz/FiO; ratio 200; (4) compatible history], or acute lung injury [same as ARDS, but PaOz/FiOz ratio 300], or are at increased risk for developing acute lung injury because of sepsis, pancreatitis, trauma, acid aspiration, radiation or chemotherapy-induced lung toxicity, and near drowning. Pulmonary edema is divided into two broad categories: hydrostatic or cardiogenic and increased-permeability or noncardiogenic edema12. Since ARDS is noncardiogenic in origin, patients with pulmonary edema due to congestive heart failure will serve as a control group.